Peroxisome proliferator-activated receptors (PPAR) are nuclear hormone receptors. PPAR receptors activate transcription by binding to elements of DNA sequences, known as peroxisome proliferator response elements (PPRE), in the form of a heterodimer with retinoid X receptors (known as RXRs). Three sub-types of human PPAR have been identified and described: PPAR-alpha, PPAR-gamma and PPAR-delta (or NUCI). PPAR-alpha is mainly expressed in the liver, while PPAR-delta is ubiquitous. PPAR-gamma is involved in regulating the differentiation of adipocytes, where it is highly expressed. It also has a key role in systemic lipid homeostasis. A number of compounds that modulate the activity of PPARs have been identified including thiazolidinediones, which have been employed in the treatment of diabetes.
The DNA sequences of the PPAR-gamma subtypes are described in Elbrecht et al., BBRC 224; 431-437 (1996). Peroxisome proliferators including fibrates and fatty acids activate the transcriptional activity of PPARs.
Numerous examples are provided in the literature illustrating that PPARs are closely involved in a wide array of diseases or pathological conditions which are associated with cells expressing these nuclear receptors. More specifically, PPARs are useful as drug target in methods for reducing blood glucose, cholesterol and triglyceride levels and are accordingly explored for the treatment and/or prophylaxis of insulin resistance, dyslipidemia, and other disorders related to Syndrome X (also designated “the metabolic syndrome) (WO 97/25042, WO 97/10813, WO 97/28149; see also Kaplan et al., 2001, J Cardiovasc Risk, 8, 211-7) including obesity and atherosclerosis (Duez et al., 2001, J. Cardiovasc. Risk, 8, 185-186), coronary artery disease and certain other cardiovascular disorders. Further, PPARs have been shown to be potential targets for the treatment of certain inflammatory diseases such as cutaneous disorders (see Smith et al., 2001, J. Cutan. Med. Surg., 5, 231-43), gastrointestinal diseases (WO 98/43081) or renal diseases including glomerulonephritis, glomerulosclerosis, nephrotic syndrome and hypertensive nephrosclerosis. Similarly PPARs are useful for improving cognitive functions in neurologic diseases (Landreth and Heneka, 2001, Neurobiol Aging, 22, 937-44) or in dementia, for treating psoriasis, polycystic ovarian syndrome (PCOS) or for preventing and treating bone loss, e.g. osteoporosis (see for example U.S. Pat. No. 5,981,586 or U.S. Pat. No. 6,291,496).
Thus, PPARs are exciting targets for the development of therapeutic compounds. Although, the responses observed in the context of the various methods for treating and/or preventing diseases or pathological conditions are encouraging for example, the thiazolidinedione, TZD, class of medications (e.g., rosiglitazone or pioglitazone) unambiguously plays a critical role in improving insulin sensitivity in patients with type 2 diabetes (see Cheng Iai and Levine, 2000, Heart Dis., 2, 326-333), they are not fully satisfactory treatments because of the occurrence of numerous serious undesirable side effects (for example, weigh gain, hypertension, cardiac hypertrophy, haemodilution, liver toxicity and oedema; see Haskins et al., 2001, Arch Toxicol. 75.425-438; Yamamoto et al., 2001. Life Sci., 70, 471-482; Scheen, 2001, Diabetes Metab., 27, 305-313; Gale, 2001, Lancet, 357, 1870-1875; Forman et al., 2000, Ann. Intern. Med., 132, 118-121 and Al Salman et al., 2000, Ann. Intern. Med., 132, 121-124). Consequently, it is desirable to identify novel improved products and/or novel methods which enable the treatment and/or the prevention of diseases or pathological conditions associated with cell types that express PPAR nuclear receptors. More specifically, most of the side effects observed with TZD derivatives are attributable to the full-agonist properties of said compounds and thus it is desirable to identify new compounds that are not necessarily full-agonists.
The thromboxane receptor is involved in blood platelet aggregation and has been implicated in vasoconstriction, as well as in bronchial and tracheal smooth muscle constriction. European patent application, publication No. 94239; European patent application, Publication No. 0 266 980 and U.S. Pat. No. 4,895,962 name certain 4-phenyl-1,3-dioxan-5-ylalkenoic acid derivatives and describe their potential utility as thromboxane receptor antagonists. Additional compounds for modulating thromboxane receptors and/or peroxisome-activated receptors (PPAR) and for the treatment and prevention of diseases associated with them are needed.